Solved

Large numbers (20 digits)

Posted on 2000-04-09
9
188 Views
Last Modified: 2010-04-02
I have string like "12345678901234567890" and I would have to convert
it to number, add one to it and convert it back to text. I can
probably come up with a complex way of doing it, but since someone has
already invented the wheel, I would like to know how this should be
done.

Somehow I had the imprsession that e.g. Roguewave's class library
(Tools.h) offers some kind of solution to this, but I couldn't find
anything from it. I believe it could be in Math++, but as I couldn't find any good documentation from Roguewave's site, I don't know if it is in it and if it is, what method it would be.
0
Comment
Question by:tonitop
  • 3
  • 2
  • 2
  • +2
9 Comments
 
LVL 1

Expert Comment

by:ntdragon
Comment Utility
you can do two thing

1)you can use strings as numbers what i mean is you"ll have to write all the operations for strings like <+,-,*,/,%>
and then you"ll have large numbers

2)you can take your string breake it to ints then do the opertion on them and build back the string

i would use the frist one i did it in the past in pascal it's not that hard
0
 

Author Comment

by:tonitop
Comment Utility
Thanks.

Those were the options I already know that can be done (not sure how), but I'm looking easier way :) I'm not making class library for handling large numbers and I only need this functionality in one function, so I'm not really interested in how it is implemented as long as it works.

IMO in OO Programming one should try to use code written by others and not spend time reinventing the wheel (which would become quite angulate :), especially if the problem is just a small part of the whole program. Of course doing something yourself teaches you, but I have to draw the line somewhere and try to learn things that are more important to my current projects.
0
 
LVL 2

Expert Comment

by:Serega
Comment Utility
If you want only to add one (or two :) ) to this number, you can add it to charcode of last digit in it. And then if last digit bigger than '9', set it to zero and add 1 to previous digit.
Something like this:

last = strlen(str_number);
str_number[last]++;
while( str_number[last] > '9' )
{
  str_number[last] = '0';
  last--;
  str_number[last]++;
}
 
0
 
LVL 1

Expert Comment

by:ntdragon
Comment Utility
i think you still can use my first idea
if you want to use only operator + it very easy to do

it like:

 123
+
 999
----
1122

you sum the last entry and move 1 or 0 to the next entry
0
Top 6 Sources for Identifying Threat Actor TTPs

Understanding your enemy is essential. These six sources will help you identify the most popular threat actor tactics, techniques, and procedures (TTPs).

 
LVL 4

Expert Comment

by:captainkirk
Comment Utility
make that_i64toa()- sorry...
0
 
LVL 4

Expert Comment

by:captainkirk
Comment Utility
oops - looks like the original comment got dropped -

If you have __int64 support (Microsoft specific), you could use _atoi64() and _i64toa() to do it...
0
 

Author Comment

by:tonitop
Comment Utility
No Microsoft in HP-UX 11 :)
0
 
LVL 4

Expert Comment

by:captainkirk
Comment Utility
HP-UX has LARGE_INTEGER, though, I believe... it's a quadword type of struct. As for API support, you would check the OS docs for that. Various flavors of UNIX treat this differently... check into that and let me know if that helps...
0
 
LVL 4

Accepted Solution

by:
inpras earned 100 total points
Comment Utility
Hi check this out this works fine for me
      unsigned __int64 i;
      char mystring[100];
      ZeroMemory(mystring, 100);
      strcpy(mystring, "12345678901234567890");
      i = _atoi64(mystring);
      i = i+1;
      _ui64toa(i, mystring, 10);

Hope this helps
inpras
0

Featured Post

How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

Join & Write a Comment

Errors will happen. It is a fact of life for the programmer. How and when errors are detected have a great impact on quality and cost of a product. It is better to detect errors at compile time, when possible and practical. Errors that make their wa…
C++ Properties One feature missing from standard C++ that you will find in many other Object Oriented Programming languages is something called a Property (http://www.experts-exchange.com/Programming/Languages/CPP/A_3912-Object-Properties-in-C.ht…
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now